Apparatus for gauging the position of liquid levels (or interfaces) in vessels



March 1955 J. J. FERRIER ETAL 2,704,391

APPARATUS FOR GAUGING THE POSITION OF LIQUID LEVELS (OR INTERFACES) IN VESSELS Filed Jan. 5, 1952 2 Sheets-Sheet l ATTO R N EYS M r 1955 J. J. FERRIER ET AL 2,704,391

APPARATUS FOR GAUGING THE POSITION OF LIQUID LEVELS (OR INTERFACES) IN VESSELS Filed Jan. 5, 1952 2 Sheets-Sheet 2 Y INVENTORS pm WM ,9

United States Patent APPARATUS FOR GAUGING THE POSITION OF LIQUID LEVELS (OR INTERFACES) 1N VESSELS Jacques J. Ferrier, Sanary, and Jacques Bou, Hyeres, France Application January 5, 1952, Serial No. 265,169 3 Claims. (Cl. 33126.5)

This invention relates to an apparatus for gauging the position of liquid levels (or interfaces) in vessels, such as open or closed tanks.

An object of the invention is to make possible such gauging in a single operation even though the tank contains two or more layers of non-miscible liquids.

Another object is to provide an apparatus of great simplicity, accuracy and efficiency.

A further object is to provide a gauging apparatus which can readily be used in connection with closed tanks, including those in which the pressure is greater or less than atmospheric.

Another object is to provide certain improvements in the form, construction and arrangement of the several parts by which the above named and other objects may eifectively be attained.

A practical embodiment of the invention is shown in the accompanying drawings, in which:

Fig. 1 represents an elevation of the apparatus installed in a tank, certain parts being in section and parts of the tank being broken away;

Fig. 2 represents a similar View to the view of Fig. 1;

Fig. 3 represents a detail horizontal section, taken on the line l]I-III of Fig. 1;

Fig. 4 represents a top plan view of the cone;

Fig. 5 represents an elevation of the cone, and

Fig. 6 represents a vertical axial section of the cone.

Referring to the drawings, the apparatus is shown as being installed in a tank having a top wall 1 and a bottom wall 2; the latter may be provided with a small well 3 for a purpose described below. The tank may be cylindrical, spherical, rectangular or any other desired shape, and is shown as being partly filled with two immiscible liquids L and L". The top wall 1 is provided with an opening 4 over which is mounted a cupola 5 containing a pair of upright supports 6, 6, shown as being secured to the sides of the cupola. In the supports 6, 6 is journaled (on suitable bearings 7, 7) the shaft 8 of the main pulley 9, the rim of which is flat with small flanges.

An auxiliary pulley or spool 10 is fixed on a shaft 11, which is journaled in supports 12, 12 and projects out through the wall of the cupola. On the outer end of the shaft 11 are fixed a hand crank 13 and a ratchet wheel 14, the latter being adapted to be engaged by a releasable pawl 15. A gas-tight packing gland 16 of any suitable type may be provided, if necessary, where the shaft 11 passes through the wall of the cupola.

The main pulley 9 is designed to carry a flat tape 17 on one end of which is attached the cone assembly 18 and the other end of which is secured to the main counter-weight 19. The tape 17 is calibrated with markings indicative of the vertical position of the cone, and a gastight window 20 in the top of the cupola permits observation of these markings as the tape passes over the top of the main pulley. The window 20 may be a magnifying lens, if desired, and is normally provided with an index line for comparison with the calibrations on the tape.

The main counter-weight 19, shown as being conical with an upwardly projecting stem 19', is somewhat lighter than the cone assembly 18. An auxiliary counter-weight 21, shown as being a hollow frusto-cone with an upwardly projecting tubular part 21, is fitted loosely around the weight 19 and stem 19' and is independently supported by a cable or cord 22 secured to the spool 10 and capable of being wound thereon when the crank 13 taken at a right angle 2,704,891 Pater. ted Mar. 29, 1955 is turned. The counter-weight 21 is heavy enough so that the total weight of the main and auxiliary counterweights exceeds that of the cone assembly 18. For ex ample, with a cone assembly weighing 3.21 kg., the main counter-weight 19 may weigh 1.78 kg. and the auxiliary counter-weight 21 may weigh 3.33 kg. (or, in any event, more than 1.43 kg.). The tape 17 may conveniently be metallic, with known coefiicients of thermal expansion and tensile elongation, and the cord 22 may be of Nylon or the like with a diameter of approximately one millimeter.

The cone assembly 18 includes an inverted conical float member 23 mounted at its apex on a vertical tube The member 23 is braced in proper position by means of the disc 25, which fits on the tube 24 with its periphery resting against the inner surface of the member 23. The float member is provided, near its apex, with one or more perforations 26 and the disc 25 is provided with the larger perforations 27. A plug 28 is screwed or otherwise fastened in the bottom end of the tube 24 and a flat bottomed solid shoe 29 is screwed onto the lower end of the plug 28. The upper end of the tube 24 is secured to a slotted member 30 and one end of the tape 17 is fastened in this member, as by means of set-screws 31. As shown in Figs. 4, 5 and 6, the upper part of the tube 24 is enlarged to accommodate a thermometer dial 32, the bulb of the thermometer extending down through the tube almost to the plug 28 and the tube being provided with perforations 33 at various levels from its bottom up to the vicinity of the dial 32. The provision of the thermometer is expressly made optional; when it is omitted the tube 24 need not be perforated, or the parts 24, 28 and 30 may be formed, in an obvious manner, as a single solid bar.

A particular feature of the float member 23 is the provision of an outwardly and downwardly curved fluted edge formed by the triangular projections 34, each of which has a sharp lower point and saw-tooth edges extending up to the circular base line which corresponds to the highest part of the edge.

In operation, assuming that the counter-weights 19 and 21 are in their lowest position and the cone assembly 18 is in its highest position in a tank containing one or more liquids the level of which is to be measured, the operator turns the crank 13 and steadily winds up the cord 22 on the spool 10. This lifts directly the counter-weight 21 and the main counter-weight 19 rises with it, due to the pull on the tape 17 exerted by the weight of the cone assembly 18 (which exceeds that of the counter-weight 19, as explained above). As the counterweights rise the cone assembly descends, eventually reaching the level of the liquid. The shoe 29 will enter the liquid with little perceptible change in tension on the cord 22, but when the float member 23 enters the liquid it tends to float thereon while the liquid enters through the perforations 26 and 27, allowing it to sink gradually; at this stage the load on the cord 22 increases sharply as the operator takes a few extra turns on the crank to lift the auxiliary counter-weight 21 out of contact with the weight 19 by a distance of about 15 inches (i. e., approximately the vertical depth of the float member), and then locks the crank-shaft 11 by means of the pawl and ratchet 14, 15. The operator then observes, through the window 20, the slow passage of the tape 17 (corresponding to the gradual sinking of the float member) and is able to note precisely the height of the liquid level by observing the instant at which the tape starts to move more rapidly, this being the instant when the highest point of the edge of the float member passes through the liquid surface. The precision of this observation is assured by the fact that the fluted edge of the float member eliminates any surface tension or capillary eflects which might cause the member to cease floating at a level lower or higher than the true liquid level. After the float member moves below the liquid level its further descent draws the weight 19 up against the weight 21 and all motion is stopped.

If a second level is to be measured (e. g., the interface between liquids L and L") the steady winding up of the card 22 is continued until the motion of the float member is slowed by immersion in the lower heavier liquid, when the observation procedure may be repeated as described above. Whenever necessary or desired, the winding may be continued until the shoe 29 touches the bottom of the tank (or bottom of the well 3) in order to establish or confirm the zero reference level. The true heights (and volumes) of the liquid or liquids in the tank can readily be formulated from the surface level readings thus obtained. In case there is danger that solid material may collect on the bottom of the tank and prevent the flat shoe 29 from resting evenly thereon, the shoe may be made in the form of a tripod, for improved average accuracy in determining the zero reference level.

The cone assembly will normally be permitted to rest on the bottom, with the counter-weight 21 supported only by its cord 22, so that there will be as little tension as possible on the measuring tape 17 and so that the zero reference level can be re-checked immediately before each measurement of the liquid level or levels. When such a measurement is to be made, the pawl is moved away from the ratchet and the crank handle is turned in the reverse direction, permitting the combined counterweights to descend and to lift the cone assembly out of the liquid, where it is held long enough for the liquid to drain out; the measurement then proceeds as previously de scribed. If the thermometer is used and the operator wishes to know the temperature of the liquid in the tank. the cone assembly is lifted all the way to the top of the tank so that the reading on the dial 32 can be observed through a second window (not shown) in the side of the 'cupola.

It will be appreciated that the control of the lifting and lowering operation by means of the crank and small spool makes it possible to lower the cone assembly into the liquid as gently as necessary, without splashing or forming ripples which might sway the apparatus and interfere with the accuracy of, the gauging. The cone assembly descends at all times in a perfectly vertical line, with no need for guide wires or the like. The construction and handling of the apparatus can be simplified and the weight reduced by making the cone and other appropriate parts of plastic material.

What we claim is:

1. In an apparatus of the character described, a float member comprising a hollow conical body having its apex at the bottom, said body being provided with one or more perforations near its apex and having an outwardly and downwardly turned fluted upper edge.

2. A float member according to claim 1 in which the flutings are in the form of triangular projections having sharp points and saw-tooth side edges, the bases of said projections lying substantially in the circular line corresponding to the highest part of the edge.

3. A float member according to claim 1 which includes a weighted shoe secured to, and projecting below, the apex of the conical body.

References Cited in the file of this patent UNITED STATES PATENTS 812,296 Horton Feb. 13, 1906 1,982,970 Star Dec. 4, 1934 2,242,603 Weldy May 20, 1941 2,282,774 Wiggins May 12, 1942 

